The present invention relates generally to the field of watercraft, and more particularly to a marine propulsion system having interchangeable parts, and specifically to a stern drive vertical drive unit adaptable for use with either a cone clutch or clutch dog shifting apparatus.
Forward-neutral-reverse shifting transmissions are well known in the field of marine propulsion units. U.S. Pat. No. 4,397,198 issued on Aug. 9, 1983 to Borgersen et al. describes one such transmission using what is commonly called a cone clutch shifting apparatus. Cone clutch systems are generally considered to be smooth shifting and capable of handling high power outputs. A less expensive alternative to cone clutch shifting systems is the clutch dog shifting apparatus, such as described in U.S. Pat. No. 4,861,295 issued on Aug. 29, 1989, to McElroy et al. Although typically less smooth shifting than cone clutch shifting systems, clutch dog shifting systems are a preferred choice for lower power propulsion systems, and they may be found on both outboard and stern drive propulsion systems.
Stern drive marine propulsion systems are typically manufactured to have a vertical drive unit including an upper gear case housing and a lower gear case housing. It is common for a cone clutch shifting apparatus to be housed in an upper gear case housing, while it is common for a clutch dog shifting apparatus to be housed in a lower gear case housing. An upper gear case housing incorporating a cone clutch shifting apparatus will be mated with a lower gear case housing containing a non-shifting power transfer apparatus to translate the vertical rotation of the vertical drive unit drive shaft into horizontal rotation of the propeller shaft. A typical non-shifting power transfer apparatus utilizes mating bevel gears disposed at right angles to each other. Similarly, the lower gear case housing of a stern drive propulsion system incorporating a clutch dog shifting apparatus will be mated with an upper gear case housing containing a non-shifting power transfer apparatus to translate the horizontal rotation of the engine drive shaft into vertical rotation of the vertical drive unit drive shaft.
The availability of both the cone clutch shifting system and the clutch dog shifting apparatus allows the manufacturer of marine propulsion systems to offer a variety of drive options to its customers. However, designing, manufacturing, and inventorying all of the individual parts necessary to provide such options can be very costly and space consuming.
Thus, there is described herein a marine propulsion system that can be configured with either a cone clutch shifting apparatus or a clutch dog shifting apparatus. A marine stern drive vertical drive unit is described herein that includes an upper gear case housing adapted for supporting either a cone clutch shifting apparatus or a non-shifting power transfer apparatus. The upper gear case housing incorporates an input shaft pinion and bearing arrangement adapted to engage the drive gear(s) of either of the cone clutch shifting apparatus or the non-shifting power transfer apparatus. The upper gear case housing also includes a lower mating surface adapted for attachment to a lower gear case housing including either a non-shifting power transfer apparatus or a clutch dog shifting apparatus, respectively.
Further, a shifting linkage is described herein that is adaptable for use in the vertical drive unit with either the cone clutch shifting apparatus or the clutch dog shifting apparatus. The shifting linkage includes a dual function shift cable and shift cable lever, along with interchangeable cone clutch and clutch dog shift links and connecting hardware.